Electrical winding



Dec. l, 1931.

A. M. WIGGINS ELECTRICAL WINDING Filed Jan. 17. 1931 lig 32 4L@ if Harn/[5555. 47%. MQ

Patented i Dec. 1,- 1,931

" UNITED v STATES PATENTl ori-lcs- ALBEBT 111:. WIGGINs, or SHARON, PENNSYLVANIA, Ass'reNon. 'ro w'nsrmenonsn Enne- 'mrc eimNUrAc'rUaINe coMrANY, A conronA'rIoN or PENNSYLVANIA ELECTRICAL WIDTDING Application illed January 17, 1931. Serial No. 509,383.

My invention relates to windings for electrical apparat-11s'l and particularly to multistrand-conductor windings of the type used in transformers, reactors, and other similar devices.

In windings designed to carry currents -sufficiently great to require a rather large cross-section of conductor, the losses from eddy-currents will be objectionably high if a single-conductor winding is used. Consequently, in suchl high-current windings,`the conductor is usually sub-divided into a plurality of parallel-.connected strands whichv are separately insulated-to reduce the eddycurrents and the losses which result from them. It is .highly important that the strands I of such conductor be so arranged that the `current will divide uniformly among them so that each strand'may be fully loaded without overloading others. This result maybe attained'by so positionallytransposing the strands that each strand. has substantiallyk the same resistance and reactance as does every other. It is to' an improved solution of of parallel paths may be p equal.,

this problem of strand transposition that my invention is directed.

Generally stated, it is the object of my invention to 'provide a winding of such cnstruction that local and `eddy-currents may be reduced to a minimum, and the impedances made essentially i which permits, during the course of the Winding, each section to occupy' a position similar to that of every other section to thereby asf `sure the' desired equal-current distribution among all parallel paths.

A further object of myinvention is to provide a scheme for accomplishing a transductor 'sections` Iis gradual, uniform andosition, lof the character above mentioned, 1n which the change of position ofthe conprogressive throughout the entire-winding. Another -object of my invention is to provide a transposition scheme which permits of a reduction toa :minimum of the distortion in ,Fig. 5.

coil shape which necessarily results at points Y where conductor sections are interchanged in position, and 'permits all coil turnsto have a more nearly symmetrical contour than has heretofore been possible.

Other ohjects of the linvention will be apparent from a description of a specific em-V bodiment thereof, when taken in conjunction with the accompanying drawings, in which,

Figure l is a view, in sectional elevation, of a transformer' of one type employing windings ofthe type to which my invention is particularly applicable. f-

Fig. 2 is a top plan view of a winding formed in accordance with my invention.

Fig. 3 is a view, in side elevation, of the winding of Fig. 2l Y j Fig. 4 is a sectional view, taken on line' IV-IV of Fig. 2.

Fig. 5 is a developed view of the iirst' or end turn of the winding of Figs. 2, 3 and 4.

Figs. 6, 7, 8, 9 and 10 are sectional views taken on .lines VI-VI,VIIVII, VIII- VIII, IX-IX and X-'-X, respectively, of

Referring to the drawings, I have shown, in Fig. 1,'a ltransformer of a well known type comprising a core 10 and primary and secondary windings 11 and 12, which are of a type to which the transposition scheme of my invention'may be readily adapted. In

' the remaining figures .of the drawings, I have illustrated the constructional features of one of' theseI windings, for instance, winding 11 of Fig. 1, the conductor of which is assumed to comprise a plurality of separate sections, A to which I have applied my scheme for transposing conductor sections. I

It will become apparent, however, as the explanation proceeds, that my transposition scheme is not exclusively Vlinut/ed to application in the windings of a transformer of the particular type shown, as it may, in addition, be applied to windings used in electrical apparatus of ai wide variety of other types.

'ReferringtoFigs 2, 3 and 4, the winding there illustrated will be seen to be ormed from conductor comprisin four parallel strands, separately insulate in the usual manner, whiclLI have designated by 1, jg 10 3 and 4, respectively, inall figures of the prises twelve turns of a four-strand conductor. In windings of a different number of turns, the same relative transpositions would "be made at equal intervals. Also, for a different number of strands, a correspondingly different number of transpositions would be required to leave the strands at the two ends of the winding in the same relative positions.

In practicing my invention, inthe preferred embodiment illustrated, I interchange the positions ofy one pair of adjacent conductor strands during the irst turn of the winding, another pair during the next turn, a third pair during the succeeding turn, and so on through the complete windlng, so that the original strand arrangement is returned to at the end of thel final turn. Hence, during the course of the complete winding, each strand occupies a position similar to that of ever other strand in the conductor.

I ave found that a uniformly distributed twisting of the air of strands positionally interchanged rediices the accompanying distortion of conductor shape to a minimum and permits all turns to have a symmetrical contour or v shape. My transposition scheme makes use of such uniformly distributed twisting in the interchanging of strand positions.

Thus, as will be seen from Fig. 4, conductor sections 1 and 2 in proceeding from the beginning of the iirst turn, or point 14, to the opposite side of the coil, or point 16, in the winding, have been so twisted through an angle of 90 degrees that they assume the re- Spective positions there shown, and, in furt er proceeding from point 16, through the succeeding half-turn, to point 17 in the winding, these same sections have been twisted through another 90 degrees, and their positions have thus been completely interchanged within the length of the first complete winding turn. f

During the second or succeeding turnV of the winding, which continues from point 17, conductor sections l and 3 are similarly interchanged in position, assuming the halfturned relation shown at point 18, and the completely interchanged relation at the end of that turn, or point 19. Similarly, in the third turn of the winding, starting from point 19, conductor sections 1 and 4 are positionally interchanged, intermediately at point 20, and completely at point 21.

During the fourth turn of the winding, ending at point 22, conductor sections 2 and "24 and 27, and 27 and 15. a

3 are similarly positionally interchanged, as are sections 2 and 4 in the succeeding turn, ending at point 23, sections 2 and 1 in the next turn ending at point 24, sections 3 and 4 in the turn ending at 25, sections 3 and 1 in the turn ending at 26, sections 3 and 2 in the turn ending at 27, sections 4 and l in the turn ending at 28, sections 4 and 2 in the turn ending at 29, and, lastly, sections 4 and 3 in the turn ending at 15, previously mentioned as completing the winding. It will be observed that the original arrangement of the conductor sections has thus been returned to at the end of this final turn.

It will be evident that, in thus progressing of three consecutive turns of the winding, the pair of adjacent strands positionally interchanged during any given turn is different from that of all other turns in the group and includes, with the exception of the iirst turn, one strand of the pair interchanged during the preceding turn. As will be seen, a similar relative selection and positional interchange of strand pairs is followed for all four groups of three consecutive turns each of which, in Fig. 4 of the drawings, respectivelyinclude the turns between points 14 and 21, 21 and 24,

The twisting of the positionally interchanged strand pair through 180 Ieed not take the whole turn len th to accomplish, should it be desirable, rom an electrical, manufacturing or other standpoint, to confine such transposition within some fractional part of the turn length. The drawings show utilization of the complete length of turn for this purpose because such modiication better lends itself to explanation of the fundamental scheme involved.

It will be evident that, in thus progressing throughout the complete winding, which, in

this case, has consisted of the twelve turns mentioned, each of the conductor sections l,

2,3.and 4 has occupied a position similar to that of everyother section in the winding conductor, and, consequently, the total lengths of the sections are all equal. Since the positions have been shown to be similar, it ,follows that the reactances, as well as the resistances, of the parallel paths will likewise be equal, and the current distribution will thus assume the described balanced relation among the several conductor sections.

As will be seen from inspection of Figs. 5 to `10, inclusive, which illustrate, in a develope/d or unrolled form, the first turn`of the winding included between points 14 and 17, the interchanging of the pair of adjacent conductor sections, sections 1 and 2, in case of this first turn, is accomplished, in the embodiment illustrated, by a gradual and uniform twisting which is distributed throughout the length of the complete turn.

the turn or point 16, the sections 1 and 2 have been twisted through 90 degrees to an onedge position, and, fat thel point where the turn is complete or 17, these same sections have been further twisted through an additional angle y0157,90 degrees to assume a comi pletey inter-changed position.` The intermediate or 45 Ldegree points are illustrated at 3() and,l 31, respectively, shown in section in Figs, 7 and 9. i

Transposi'tion `of the adjacent sections 1 and Sin thesecond-zturn is accomplished in an exactlyA similar, manner, and, for the other pairs or adjacent sections in the succeeding turns,.the method used is also that which has been described for thek first turn.v

The advantage of this uniform twisting method or transposition, entirely apart from providing means to obtain the required unilform distribution of current already considered, lies in the small amount of distor- .tion of, coilshape thereby produced, and is effective when the strand-pair interchange takes' place in the exact or complete turn length orl some fraction or multiple thereof. This feature, aswill be recognized, is an exceedingly valuable one, particularly in coils in which themaximum number of ampere tuis must be crowded into a closely limlted s ace. l

pIt will be appreciated that, in using this method, a `fixed relation is maintained between the number of sections in the conductor and the total number of turns in the complete winding. If, ashas been illustrated,

one ypair or adjacent strands is positionally interchanged during the exact length of each complete winding lturn, toobtain complete transposition, the number of turns required equals the Inumber of conductor sections'in parallel, multiplied by a quantity equal to the numberv of sections less one; that is, ir n designates the number of parallel strands, the number of winding turns t yrequired to eii'ect a complete transposition is given by the expression t=fn,(n1)7. In the winding that I haveshown and de# scribed, the number of turnsrequired by this formula will be four multiplied by the quantity four minus one, or a total of twelve,l

which,it will be observed, is the number illustrated. n

It will be evident that, while I have shown,

l and so far described, the positional interchanging of a pair of strands by twisting through Van ang e of 180 degrees, as taking place within the exact length of a winding Other sizes of conductor section can, of course modification is made, the relation between the number of conductor strands and total turns of the winding required for complete transposition becomes exceedingly exible and no longer limited "by the expression t=n(n1); the expression applying to such modificationv being t=fn,('n*1).

It will' be further evident that, vwere a number of conductors 7c, each having the construction shown -in the drawings, to be wound side by sidelinto a coil, the number of turns necessary to complete the transposition, on l the basis Orione strand pair per turn, would still remaintw'elve,in spite of the fact that the cross-sectionof the total conductor has been increased by the fact-or k, because each of the 7c similar conductors could transpose its strands independently of the others or, in a parallel manner, as might be desired. By using such a parallel-conductor scheme, it is evident that the total turns required may, in many cases, be correspondingly reduced, and the application of my invention be thereby further broadened.

The relative dimensions of width to thickness of the individual sections nowcommercially used in multi-section conductors are such tlratthey readily lend themselves to use in this transposition scheme, they beingof the general order of two to one. It will be noted that such ratio, that is, a section Width which is twicey the thickness, "has been illustrated in the drawings and it can be seen that these particular proportions givea minimum amount of conductor-shape distortion due to the twisting of the sections vor strands.

be used with but slightly less advantage. a

Although I have shown and described a certain specific embodiment of my invention, I am fully aware that many modifications thereof are possible. My invention, thereforeis not to be restricted except insofar as is necessitated by the prior art and by the spirlt of the appended claims.

I-claim as my invention:

' In a Winding for electric apparatus com- I prising a plurality of turns of conductor of ',n parallel strands, a system of strand rtransposition in which the adjacent strands of one pair have their positions interchanged by progressive twisting of the pair through an angle of 180 during an-exact fraction or multiple ai of turn'length Z, a different pair of adjacent strands being, thus positionally interchanged during each succeeding conductor length mZ in such manner that, in progressing through .-1L(n,1) turns of the winding, the active-| lengths of all strands y become substantially equ'al'and each occupies' a position similar to that'of every other strand inthe conductor.

2. In a winding forv electrical apparatus comprising ft turns of conductor having .frt parallel strands disposed concentrically with the axis of the winding, a system of strand transposition in which one pair of adjacent strands is twisted during the length of each complete turn of the winding through an angle of 180 to effect an interchange in the respective positions of the strands comprising said pair, said system being so deL veloped that, in each group of 0i-1) consecutive turns of the winding, the pair of adjacent strands so positionally interchanged during any given turn is different from that of all other turns in the group and includes, with the exception of the rst turn, one strand of the pair interchanged during the preceding turn, a similar selection and positional interchange of strand pairs being followed for all groups of (n.-l),'" consecutive -turns, said groups being of such a number that the total turns t in the winding equals n multiplied by UL-1).

3. A winding for electrical apparatus comprising t turns of a common mean diameter `wound from a conductor having n parallel strands of equal rectangular cross-section disposed in the winding concentrically with the axis thereof, in which one pair of adjacent strands istwisted during an exact fraction or multiple m ofturn length l through an angle of 180 to effect an interchange in the respective positions of the strands comprising said pair, and in each group of (fz-1) consecutive turns of the Winding the pair of adjacent strands so positionally interchanged during any given conductor length mZ is different from that of all other corresponding lengths in the group and includes, with the exception of the first length, one strand of the pair interchanged during the preceding length, a similar selection and positional interchange of strand pairs being followed for all groups of (n-1) consecutive turns, said groups being of such a number that the total turns t in the winding. equals n multiplied by um 4. In a winding for electrical apparatus comprising t turns of conductor having n parallel strands disposed concentrically with the axis of the winding, a system of strand transposition in which one pair of adjacent strands is twisted during an exact fraction or multiple of turn length l through an angle of 180 to eieet an interchange in the respective positions of the strands comprising said pair, said system being so arranged that, in each group of gita-1) consecutive turns of the Winding, the pair of adjacent strands so positionally interchanged during any given conductor length mi is different from that of all other corresponding lengths in the group and includes, with the lexception of the first length, one strand of the pair interchanged during the Jpreceding length, a similar selection and positional interchange of strand pairs being followed for all groups of mM-1) consecutive turns, said groups being of such number that the total turns t in the winding equals n multiplied by (n- 1) 5. A winding for electrical apparatus co'mprising t turns of a common mean diameter wound from a conductor having n parallel strands of equal lrectangular crosssection disposed in the winding concentrically with the axis thereof, in which one pair of adjacent strands is twisted during the length of each completeturn of the winding through an angle of 180 to effect an interchange in the respective positions of the strands comprising said pair, and in each group of Ut-1) consecutive turns the pair of adjacent strands so positionally interclianged during any given turn is different from that of all other turns in the'group and includes, except for the rst turn of the group, one strand of the pair interchanged during the preceding turn, a similar selection and positional Vinterchange of strand pairs being followed for all groups of UL-1) consecutive turns, which groups are of such number that the total turns t in the winding equals n multiplied by cc(n l)n 6. In a winding for electrical apparatus comprising t turns of conductor having n layers of parallel strands disposed concentrically with the axis of the'winding, each of said layers including lo strands disposed axially side by side, a system of strand trans-. position in which one pair of concentrically adjacent strands in each of the k axialstrand-layer divisions is twisted during each exact fraction ormultiple of winding turn length l through an angle of 180 to effect an interchange in the respective positionsof the strands comprising said pair, said system being so arranged that, in each group of m(n-l) consecutive turns of the winding, the pair of concentrically adjacent strandsin each of the lo layer divisions so positionally interchanged during any given conductor length zal is different from that of all other corresponding lengths yin the group and includes, except for the first length, one strand of the pair interchanged during the preceding length, a similar selection and positional interchange of strand pairs being followed for all groups ot fam-1) consecutive turns said groups being of such number that the total turns t in the Winding equals n multiplied by (7a/ 7.

In testimony whereof I have hereunto subscribed my name this 13th day of January,

ALBERT MARCUS WIGGINS. 

